Sifakas Avahis and Indris: Indriidae

Physical characteristics: The indris are the largest living prosimians (or "before apes"). They weigh 13.2 to 16.5 pounds (6 to 7.5 kilograms). Head and body length is about 23.6 inches (60 centimeters). The tail is stubby.

An indri is mostly black with white areas. A black hairless face has large tufted ears and a pointed nose area. Large eyes are yellow. Body hair is long and silky. Feet have strong big toes, and long hands have strong thumbs, creating a very powerful tree branch grasp. A special throat sac enables indris to make loud sounds.

Geographic range: Indris are found in northeastern Madagascar.

Baby indris cling to their mother's underside for four months, and then begin riding on her back. (Photograph by Harald Schütz. Reproduced by permission.)

Habitat: Indris live in humid moist forests from sea level to 6,000 feet (1,830 meters).

Diet: Indris eat leaves, flowers, and fruits. When these foods are hard to find, the indri uses its tooth comb to scrape tree bark and dead wood as food.

Behavior and reproduction: Indris are diurnal, moving about only in the daytime. They live in social groups of two to six members, usually a male and female pair and their young. Female indris are dominant, or in charge. However, males are responsible for defending group feeding territory, which they mark with scent glands.

Indris are arboreal, living in trees. They leap between tree trunks. Leaps can be as long as 33 feet (10 meters). Indris seldom move on the ground; when they do, they walk upright, moving forward by hopping and holding their somewhat short arms above their body. At night, before going to sleep, indris have a group grooming session.

Indris begin mating at seven to nine years old. There are two to three years between births. Only one offspring is born each time. Tiny babies cling to the mother's underside until four months of age, then begin riding on her back. Leaping practice begins at this time. By eight months of age, young move about by themselves, although they stay with the parents for about two years.

Indris sound like a clarinet, a musical instrument, early in the morning. These calls can be heard up to 2 miles (3 kilometers) away. The indris are very territorial, making shrill cries warning other groups to stay away. There are also loud howling or singing sessions by group members. These howling songs can last up to four minutes. Other sounds made by indris include hooting and barking to warn of nearby predators, and grunts and wheezes when frightened.

Indris and people: In many areas there are local taboos against people harming indris, however hunting does occur.

Conservation status: Indris are considered Endangered, facing a very high risk of extinction, due to logging, hunting, and slash-and-burn agriculture (cutting down trees and burning remnants to clear land for farming). ∎